Provided are a printing apparatus and a conveying-error controlling method capable of printing a high-quality image by correction reflecting the conveying amount of a printing medium. A provided inkjet printing apparatus prints images by printing scans for actual printing and by conveying the printing medium with a roller orthogonally to the printing-scan direction. In each printing scan, the printing medium is scanned with a print head having an array of nozzles from which the ink is ejected. The print head moving direction differs from the arranging direction of the nozzles in the array. The apparatus includes a conveying controller to control the conveying of the printing medium on the basis of a correction value used to correct a conveying error of the roller. The conveying controller changes the correction value to be applied in accordance with the conveying amount of the printing medium between two scans with the print head.